The many faces of human prion diseases in Belgium and the world

Prion diseases are rare neurodegenerative disorders that always lead to dea th and that can be transmissible under certain conditions. Although sporadi c Creutzfeldt-Jakob's disease (CJD) is the best known human variant of thes e transmissible spongiform encephalopathies with an incidence of about 1 in 106 inhabitants, several other types of human prion disease have been desc ribed (e.g. Familial CJD, Gerstmann-Straussler-Scheinker syndrome, Fatal Fa milial Insomnia,...). In 1996, a variant of CJD has been linked to the epid emic of bovine spongiform encephalopathy (BSE). Therefore, vigilance concer ning prion diseases was increased throughout the whole of Europe. In Belgiu m, a comprehensive, nation-wide study has been conducted both retrospective ly (1960-1997) and prospectively (1998-...) to identify prion disease patie nts. In 1998, a surveillance system has also been created to monitor the in cidence of CJD and other prion diseases. Using data from both studies and t he surveillance program, the occurrence and phenotype of all types of prion diseases in Belgium was investigated. The sporadic type of CJD was identif ied in 116 patients, while 4 suffered from a hereditary form. In our series , we could find no evidence for variant or iatrogenic CJD, neither for the more rare types of prion diseases.